Remove leaves from the fresh rosemary and place them in the shaker. Add the lime juice and muddle. Add several cubes of ice and stir vigorously. Double-strain (use a cocktail strainer on the shaker and a screened strainer over the glass, to catch the rosemary fragments) into a cocktail glass. No further garnish.

Unless you dump a truly apocalyptic volume of MiracleGro (and please don't dump any amount of MG anywhere; it's our water supply too) on the plant, rosemary doesn't produce leaves anywhere near large enough for smacking them to have effect, and they're stiff and fibrous, not moist and filled with sweet, sweet oils.

But if you swap basil in for the rosemary, smack away. Same goes for any broadleaved herb (mint--but I submit that you don't want that in this drink, bay--which may be pretty interesting, et cetera), but not so much for things like rosemary (eg, savory, sage, Herb--which, um, you probably don't want to put that in a drink either).

For those lost: Mark is talking about the very much appropriate, with the appropriate herb, practice of rinsing the leaves, cupping them in one hand, clapping sharply on them above the drink, and then placing them in the drink. This is a far better way to extract the essential oils from those broadleaved herbs than muddling is. Yes, even in a mojito, despite what most cocktail books say. Try it some time!